oleg at pobox.com writes:
> Thus we have reduced the problem of excluding certain types from a
> typeclass to the problem of excluding all types from one particular
> typeclass: Fail. How can we prevent the user from adding instances to
> Fail?
By not exporting its name?
--
__("< Marcin Kowalczyk
\__/ qrczak at knm.org.pl
^^ http://qrnik.knm.org.pl/~qrczak/